"The balloon is so large that it is going to take at least two weeks to assess the whole thing - and the whole balloon will have to be rechecked - so we're probably going to miss this year's weather window," said Brian Jones, the mission control chief.

Technicians said it was possible a twist in the balloon as it came off its storage drum led to a pressure build-up at the top of the envelope splitting open a seam.

The ascent off the coast of Cornwall was already delayed 24 hours due to adverse cloud conditions on Tuesday.

But meteorologists' forecasts of a favourable north-easterly wind for Wednesday morning proved correct and the launch ship, which had been moored off St Ives, was moved to the lift-off zone about 10 to 20 miles (16 to 32 kilometres) out at sea.

The launch was due to take place at 0830 BST (0730 GMT).

Bulging flight

At the time that the failure occurred, Andy Elson and Colin Prescot were being fitted into their spacesuits prior to climbing into the balloon's gondola.

"It was very sudden when the balloon came down," said Colin Prescot.

When I arrived in Cornwall on Monday, the staff at my hotel joked that the balloon would never get off the ground.
'It's the Cornish jinx,' they said